arm64 places the CMA in ZONE_DMA32, which is not good enough for the
Raspberry Pi 4 since it contains peripherals that can only address the
first GB of memory. Explicitly place the CMA into that area.
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>
---
Changes since v1:
- Move into bcm2711.dtsi
arch/arm/boot/dts/bcm2711.dtsi | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/arch/arm/boot/dts/bcm2711.dtsi b/arch/arm/boot/dts/bcm2711.dtsi
index 1f3acd3363ea..6000a01652fa 100644
--- a/arch/arm/boot/dts/bcm2711.dtsi
+++ b/arch/arm/boot/dts/bcm2711.dtsi
@@ -12,6 +12,26 @@
interrupt-parent = <&gicv2>;
+ reserved-memory {
+ #address-cells = <2>;
+ #size-cells = <1>;
+ ranges;
+
+ /*
+ * arm64 reserves the CMA by default somewhere in ZONE_DMA32,
+ * that's not good enough for the Raspberry Pi 4 as some
+ * devices can only address the lower 1G of memory (ZONE_DMA).
+ */
+ linux,cma {
+ compatible = "shared-dma-pool";
+ size = <0x2000000>; /* 32MB */
+ alloc-ranges = <0x0 0x00000000 0x40000000>;
+ reusable;
+ linux,cma-default;
+ };
+ };
+
+
soc {
/*
* Defined ranges:
--
2.23.0
